Help choosing coupling caps

Thanks to all those that have posted
I will more then likely replace my amps stock coupling caps with Mundorf Silver and Oil.
I've heard these are very sweet sounding and seem to have what I need and should be a good match with teflons.

Musicfile, IME **all** paper and oil capacitors can exhibit an electrical leakage over time that can wreak havoc in your amplifier if used in the output section. This is because the electrical leakage will mess with the bias voltage on the grids of the power tubes.

The Mundorf is the best of the paper and oils, and rivals the Best Teflons like the V-Caps for sound. You can avoid some of the leakage issues by going with a higher voltage part, but then the size of the part gets outrageous.

So your best choice for the output section of any tube power amplifier is probably the V-Cap Teflon. It is a very neutral part, and despite claims otherwise, does not exhibit a break-in characteristic, like all Teflons (however, you will likely experience something that **sounds** like the cap breaking in for about 150 hours or so, this is actually the wiring of the circuit that was disturbed by the installation of the parts).

IME the part is very smooth, but also very detailed, a combination that is always rare and wonderful in the audio world. Be careful not to handle the part too much; Teflons do not have a curing quality (part of the reason why they also do not have a break-in time), so the part can be easily damaged if you handle it a lot. However once in circuit they are quite reliable, so long as the circuit does not come anywhere near the rated voltage of the part.

When installing the caps, do your best to keep the lead lengths and layout as short and as straight as possible.

Thanks Atmasphere for your informative reply's

I'm hesitant to use vcaps both in my pre amp and amps
I feel i'm going to get too much of a detailed sound something i'm trying to avoid
In terms of leakage I realize using teflons avoids this however were speaking long term when discussing possible cap leakage. Is that correct?

Anyone have any experience with the Russian k40 as coupling caps in tube amps.
I heard these work very well with teflons

Musicfile, FWIW, there is no such thing as 'too much detail'. Also FWIW a lot of people associate brightness with detail, the two have nothing to do with each other.

IOW you can have an extremely detailed system that is at the same time very relaxed and easy to listen to. The Teflon caps will help you get there, as they add to detail without also adding brightness, so you can get a relaxed sound.

However, due to the fact that you have to let the amp or preamp settle down after the upgrade, I would not ascribe any attributes to the system until a good amount of run time has elapsed. Otherwise you might never discover what was/is possible.